As an example of a projection type display device such as a projector, there is a device that includes a light source and an optical modulator configured to modulate light from the light source based on image information. The light modulated by the optical modulator is projected as an image through a projection lens to a screen or the like.
In many cases, such a projection type display device includes a lens array for making uniform the illuminance distribution of light emitted from a light source to suppress uneven luminance of light projected to the screen.
However, in order to provide a device having a simple configuration, JP2006-126394A (Patent Literature 1) discloses a display device that includes no lens array.
The display device described in Patent Literature 1 includes an optical modulator that modulates illumination light incident on an active region, a light emitting device that has a light emitting unit roughly similar in profile to the active region of the optical modulator, and a critical illumination system that causes a luminous flux to enter from the light emitting device as illumination light to the active region of the optical modulator.
The critical illumination system forms an image of the light emitting unit of the light emitting device on the active region of the optical modulator. In other words, the light emitting unit and the active region of the optical modulator are in a conjugate relationship with each other.